Aileron of variable-a



A. F. ZAHM.-

AILERON 0F VARIABLE ASPECT RATIO. APPLICATION FILED APR. 28, 1916.

1 ,326,O 1O. Patented Dec. 23, 1919.

amvcmfoz ALBEETE ZAHM.

G How 21;;

designate like or ALBERT F. ZAHM, or BUFFALO, ivnw Yortx.

Specification of Letters Patent.

AILERON OF VARIABLE-,ASPECT RATIO.

Patented Dec. 23, 1919.

Original application filed March 26, 1914, Serial No. 827,485. Divided and this application filed April 28,

i at p 1916. Serial No. 94,135.

To all whom it may concern: h

Be it known that I, ALBERT F. ZAHM, a citizen of the United States, residing at Buffalo, in the county of Erie and State of New York, have invented certain new and useful Improvements in Ailerons of Variable-Aspect Ratio, of which the following is a specification.

My invention relates to flying machines and more particularly to an improved .method or means for varying the useful Wind force on supporting or control surfaces, such as the wing, aileron, rudder or other aerofoil, without altering its angle of incidence.

In reading and constructing the ensuing specification and the appended claims, it is to be understood that many non-essential changes in matters of detail may be made without departing from the spirit of the invention as originally conceived, or as de scribed in an application filed by me March 26, 1914, S. N. 827,485; and that the use of this invention is not limited to what I may term balancing controls alone but may be employed wherever it is desired to vary the wind force at an angle to the direction of the air rush in flight without altering the angle of incidence.

As pointed out in the application above referred to, I contemplate changing or varying the lifting force or efliciency of an aerofoil by changing itsaspect ratio-41. a, the ratio of its length to that of its chord.

In describing my invention in detail, reference will be had toaccompanying drawings wherein like characters of reference corresponding parts throughout the several views, of which:

Figure 1 is an end elevation of the planes of a biplane equipped with variable superposed ailerons -of a construction comprehended in the present case, and

Fig. 2 is a plan view of the device of my invention as illustrated in Fig. 1 except that the wing posts interconnecting the Wings are shown in transverse section.

In the form of my invention selected for illustration, 10 designates a vertical wing post secured at its opposite ends to the wing beams (not shown) of superposed planes or supporting surfaces 11 and 12. On this post is fitted a rotating sleeve 13 carrying a pair of ailerons 14 and 15, each having its pper surfa e converted and its lo er surface plane. The lower surface may be, if desired, concaved. In Fig. 2, theailerons .are shown in full lines extending perpendicular to the lineof flight and in dotted lines at an angle to their normal perpendicular plane. In the dotted line position which may be conveniently termed fore and aft the ailerons exert practically no lifting power. By turning the sleeve 13 on the post 10, however, the ailerons may be swung through any desired angle until the maxi mum change is produced when they are in the full line position illustrated. Between the dotted line position and the full line position, in whichever direction the ailerons are turned, their lifting force is roughly proportionate to their angle of displacement. In other Words, the lifting force of the aileron is changed by changing its aspect ratio.

Assuming one or more of these ailerons to be located at each end of the main planes or supporting surfaces 11 and 12, and both sets to be normally perpendicular to their line of flight with all control cords connected from the shoulder fork (common to the Curtiss type of flying machines), or its equivalent, to the sleeve 13 through an operating rod 16, then the pilot by moving the shoulder fork may swing either pair out of its fore and aft position through an increased angle up to the full line position and thereby accordingly lift that side of the machine. Details of the control are thought unnecessary as the method of operation will be sufllciently apparent without them. The vertical post 10 can be replaced by an inclined post, and according to the inclination of the post the ailerons may be disposed at either a negative [or positive angle of incidence to accordingly exert either lift or depression. It is, however, essential. that the ailerons be fixed against vertical displacement and at a 90 angle to the wing post 10. That portion of each aileron extended forwardly beyond the wing post in the fore and aft position of the aileron is somewhat shorter than that portion extended aft, and in its swinging movement is adapted to work toward the center longitudinal axis of the machine as illustrated in Fig. 2. The rear portion of each aileron is of a length to freely swing in either direction without contact with the rear wing post, herein designated 17. Any kno n means may be prQVid d to take p the vertical thrust incident to rotation of the sleeve 13 about an axis normal to the chord of the ailerons.

The ailerons which I have disclosed herein may be readily adapted for use as elevators', vertical or horizontal stabilizers. The-entire invention, or any part of it, may also be applied to lighter-than-air machines as well as to the heavier-than-air type biplane specifically described. Such variations in the application of my invention are fully contemplated by me and are intended tobecovered hereby and included in so far as'they fall fairly within the scope of the subj'oined claims.

What is claimed is:

1 A fiyingzmaclline including a balancing surface having an axis of rotation normal to its chord whereby no change whatsoever in'the efl'ectiveangle of incidence of the balancing surface is produced through its rotation about said axis, said balanclng surface being further provided with a length to width ratio of such magnitude that its rotation about its axis materially varies its lift value, together with means for rotating said balancing surface. v

2. A flying machine including a balan'cing surface havingan invariable angle of incidence, said surface being rotatable about an axis at right angles to its chord, the lift value of the balancing surface being variable, such variation being due to the high aspect ratio by which the surface is characterized together withmeans for rotating the balancing surface about said axis, said surface presenting the same angle of incidence to the air irrespective of its relative position.

In testimony whereof I atlix my signature.

ALBERT F. ZAHM. 

